Mathematics trick proof.

[Eric the Orange]

This is a trick proof I learned today and I thought was interesting so ima share it with you all.

First set up parameters,

X=Y=(whatever you want here, like your friends IQ)

Knowing this you can see these following things,(Note the ^2 is squared)

X=Y
Y=X
X^2=Y^2

By those you can figure out

XY=Y^2
XY=X^2

So finally you get to the proof proper and with some algebra you get,

XY-Y^2=X^2-Y^2
Y(X-Y)=(X+Y)(X-Y)
Y=X+Y
X=0

So though this you have definitively proven that whatever you set X equal to in the beginning is 0.

Now obviously this isn't true but it LOOKS true. I wanna see if you all can figure out the "trick". I'll come back later and explain it either way.

 

[DoPo]

Without looking at the..."proof", you're dividing by zero at some point. It's a very common trick and that's actually why you're told not to divide by zero.

Now let me look at it.

...

Aha, there you go:

Y(X-Y)=(X+Y)(X-Y)
Y=X+Y

X-Y is the same as X-X or Y-Y (since X=Y), thus zero and you divide by it.

EDIT: Actually, why didn't you go with 2=1 - it's much more than a mindfuck than X=0 when somebody sees it first:

Y=X+Y
Now substitute from the initial X=Y and you get
X=X+X
do the addition
X=2X
divide by X and
1=2

 

[BrotherRool]

Beaten to it It's not a bad trick, although I agree that you should have gone with 1=2 because the intersection of people who understand X,Y can equal whatever easily and who don't know about the dividing by 0 trick is probably smaller than people who are impressed with 1=2 and don't know the trick

Or you could just do the .999999...=1 proof and watch all the people try to work out the 'trick'

 

[Pinkamena]

As DoPo said, you're dividing (X-Y) with (X-Y). 0 divided by 0 is undefined and cannot be used.

 

[thesilentman]

Yeah, you're still dividing by zero. It doesn't work. I also remember this as some guy tried to pull this one on me and I shut him down by pointing this out. -.-

 

[madwarper]

If you really wanted to use a mathematical sleight of hand to confuse someone, I prefer using the "30th Dollar" story.

Spoiler

There are 3 businessmen on a trip. They decide to stay over night in a hotel, fortunately the only room open is a triple. The men agree to share it and split the cost evenly, which costs $30.

So, how much does each man pay to split the cost evenly? ___

Ok, the men check into the room and get settled. Later on, when the night clerk comes on, he goes over the books and sees that there's currently a discount on triple rooms and the 3 men had been overcharged. The room actually costs $25. He calls over Johnny the Bellhop, gives him 5 $1 bills and tells him to give the men the refund. Now, Johnny the Bellhop is a bit dishonest and knows that 5 doesn't divide into 3 evenly. He takes 2 $1 bills and puts them into his pocket.

So, how much is in Johnny's pocket? ___ How much is in his hand? ___ How much is in the cash register? ___ And that total is? ___

Ok, Johnny arrives at the triple room, knocks at the door, tells them they had been overcharged and gives them the 3 $1 bills as a refund.

So, how much did each man pay originally? ___ How much did each man get back? ___ So, the each men ended up spending? ___ How much did the 3 men end up paying? ___ And, add the $2 in Johnny's pocket, how much is that? ___ Where's the 30th Dollar?

Spoiler: How they're expected to answer

So, how much does each man pay to split the cost evenly? $10
[...]
So, how much is in Johnny's pocket? 2 $1 bills How much is in his hand? 3 $1 bills How much is in the cash register? $25 And that total is? $30
[...]
So, how much did each man pay originally? $10 How much did each man get back? $1 So, the each men ended up spending? $9 How much did the 3 men end up paying? $27 And, add the $2 in Johnny's pocket, how much is that? $29 Where's the 30th Dollar?

 

[Hero in a half shell]

Or you could just do the .999999...=1 proof and watch all the people try to work out the 'trick'

Oh, we tried that once on this forum.... let's just say things got so crazy that it got into a Cracked.com article!

 

[DoPo]

Or you could just do the .999999...=1 proof and watch all the people try to work out the 'trick'

Oh, we tried that once on this forum.... let's just say things got so crazy that it got into a Cracked.com article!

Really? Can I have a link, that'd be funny to see.

If you really wanted to use a mathematical sleight of hand to confuse someone, I prefer using the "30th Dollar" story.

And the actual correct answer of course is

Spoiler

There is no 30th dollar because that's an incorrect operation that goes on there - once you realise they've spent 27 dollars, there is nothing do add - from their point of view, they first spent 30 then got 3 back. The two bucks are already covered in this sum, so adding them again is nonsensical.

 

[Lionsfan]

Or you could just do the .999999...=1 proof and watch all the people try to work out the 'trick'

Oh, we tried that once on this forum.... let's just say things got so crazy that it got into a Cracked.com article!

Really? Can I have a link, that'd be funny to see.

If you really wanted to use a mathematical sleight of hand to confuse someone, I prefer using the "30th Dollar" story.

And the actual correct answer of course is

Spoiler

There is no 30th dollar because that's an incorrect operation that goes on there - once you realise they've spent 27 dollars, there is nothing do add - from their point of view, they first spent 30 then got 3 back. The two bucks are already covered in this sum, so adding them again is nonsensical.

The Cracked Article [http://www.cracked.com/blog/6-innocent-sounding-topics-that-are-guaranteed-flame-wars/], unfortunately (fortunately?), the actual topic on here got locked. But yeah......that was a nasty discussion, worse than some of the feminism threads

 

[DoPo]

The Cracked Article [http://www.cracked.com/blog/6-innocent-sounding-topics-that-are-guaranteed-flame-wars/], unfortunately (fortunately?), the actual topic on here got locked. But yeah......that was a nasty discussion, worse than some of the feminism threads

That was funny, lol! While I haven't seen the thread, I can just imagine how it went...mmm, that would have been...interesting

 

[Hero in a half shell]

Or you could just do the .999999...=1 proof and watch all the people try to work out the 'trick'

Oh, we tried that once on this forum.... let's just say things got so crazy that it got into a Cracked.com article!

Really? Can I have a link, that'd be funny to see.

If you really wanted to use a mathematical sleight of hand to confuse someone, I prefer using the "30th Dollar" story.

And the actual correct answer of course is

Spoiler

There is no 30th dollar because that's an incorrect operation that goes on there - once you realise they've spent 27 dollars, there is nothing do add - from their point of view, they first spent 30 then got 3 back. The two bucks are already covered in this sum, so adding them again is nonsensical.

http://www.cracked.com/blog/6-innocent-sounding-topics-that-are-guaranteed-flame-wars/

Read the article, read the thread. Hours of fun!

 

[DoPo]

http://www.cracked.com/blog/6-innocent-sounding-topics-that-are-guaranteed-flame-wars/

Read the article, read the thread. Hours of fun!

Sorry, man, Lionsfan ninja'd you. And the thread appears to have been purged by fire.

But I did read the article and it did give me minutes of fun.

 

[Vhite]

Why not include PEMDAS as well to start proper "discussion".

8/2*(5-1)+1 = ?

 

[That Guy Ya Know]

Why not include PEMDAS as well to start proper "discussion".

8/2*(5-1)+1 = ?

If the person writing the equation did their job properly you shouldn't have to use PEDMAS. It's one of those useless things you learn in school and never use again

 

[Vegosiux]

Why not include PEMDAS as well to start proper "discussion".

8/2*(5-1)+1 = ?

If the person writing the equation did their job properly you shouldn't have to use PEDMAS. It's one of those useless things you learn in school and never use again

Kinda hard to write an equation "properly" on a forum like this, though...and I must be a bit snobby right now, but this is far from any real math to begin with.

Still if it makes people interested it's okay.

 

[platinawolf]

8/2*(5-1)+1 = ?
Paranthesis and exponents, thus 8/2*4+1
Division and multiplication, (8/2)*4+1 = 8*4/2+1 = 17
Ofcourse, alternative solution is: 8/(2*4)+1 = 2,,,

What one is right? I know a math teacher who'd say both answers are correct as the original statement can without doubt be interpreted both ways.

 

[Vhite]

8/2*(5-1)+1 = ?
Paranthesis and exponents, thus 8/2*4+1
Division and multiplication, (8/2)*4+1 = 8*4/2+1 = 17
Ofcourse, alternative solution is: 8/(2*4)+1 = 2,,,

What one is right? I know a math teacher who'd say both answers are correct as the original statement can without doubt be interpreted both ways.

17 of course. It's just that some people tend to think that when removing parentheses you also have to multiply right away.

Why not include PEMDAS as well to start proper "discussion".

8/2*(5-1)+1 = ?

If the person writing the equation did their job properly you shouldn't have to use PEDMAS. It's one of those useless things you learn in school and never use again

It gets even worse when you are learning programming where you have many more operators. Of course there you can also use parentheses but you have to know it in school.

 

[excalipoor]

8/2*(5-1)+1 = ?
Paranthesis and exponents, thus 8/2*4+1
Division and multiplication, (8/2)*4+1 = 8*4/2+1 = 17
Ofcourse, alternative solution is: 8/(2*4)+1 = 2,,,

What one is right? I know a math teacher who'd say both answers are correct as the original statement can without doubt be interpreted both ways.

The alternative solution is wrong, despite what your mnemonics tell you. Multiplication isn't a higher priority than division, neither is addition higher than subtraction.

 

[ViciousTide]

Prove that a^n = b^n + c^n has no nonzero integer solutions for n>2.

The Millennium Prize Problems are seven problems in mathematics that were stated by the Clay Mathematics Institute in 2000. As of March 2013, six of the problems remain unsolved. A correct solution to any of the problems results in a US$1,000,000 prize (sometimes called a Millennium Prize) being awarded by the institute. The Poincaré conjecture, the only Millennium Prize Problem to be solved so far, was solved by Grigori Perelman, but he declined the award in 2010.

1) P = NP
The question is whether, for all problems for which an algorithm can verify a given solution quickly (that is, in polynomial time), an algorithm can also find that solution quickly. The former describes the class of problems termed NP, whilst the latter describes P. The question is whether or not all problems in NP are also in P. This is generally considered one of the most important open questions in mathematics and theoretical computer science as it has far-reaching consequences to other problems in mathematics, and to biology, philosophy[1] and cryptography (see P versus NP problem proof consequences).
"If P = NP, then the world would be a profoundly different place than we usually assume it to be. There would be no special value in 'creative leaps,' no fundamental gap between solving a problem and recognizing the solution once it?s found. Everyone who could appreciate a symphony would be Mozart; everyone who could follow a step-by-step argument would be Gauss..."
? Scott Aaronson, MIT
Most mathematicians and computer scientists expect that P≠NP.

2) Getting paid at work to think freely in cyberspace and by writing comments all day..
More at wikipedia: "Millennium_Prize_Problems"